Mapping Mountains – Hill Reclassifications – Humps

Pen Gilfach-y-rhew (SN 458 223) – Subhump deletion

This is the seventh in a series of Hill Reclassification posts that detail hills whose status has been altered in the listing of the Humps (HUndred Metre Prominences) through map study and / or surveys that I have instigated.

The hill name used in this and forthcoming posts is that used in the listing of Humps, therefore individual names and their composition may not match those that are used in listings I am directly associated with.  However, I am of firm belief that listed hill names used by other authors should be respected when giving detail within other people’s lists, however inappropriate some hill names may be considered.

This and forthcoming posts are retrospective as many of these hill reclassifications were initiated from studying the Ordnance Survey enlarged mapping that is hosted on the Geograph website, and for the reclassifications that affected the Humps the email I posted on the RHB Yahoo Group forum in relation to this hill was dated 01.05.12.

The listing of Humps was published in book format by Lulu in 2009 and entitled More Relative Hills of Britain, its author; Mark Jackson gives credit to a number of people who contributed toward the formation of this list, these include; Eric Yeaman, Alan Dawson, Clem Clements, Rob Woodall, Bernie Hughes, Pete Ridges and others.  When the list was published in book format there were 2987 Humps listed with their criteria being any British hill that has 100m or more of drop, accompanying the main list is a sub category entitled Subhumps, with the criteria being any British hill that has 90m or more and below 100m of drop.

More Relative Hills of Britain by Mark Jackson

The details for the reclassification appear below:

There has been a reclassification to the listing of the Humps (HUndred Metre Prominences) due to consulting the Ordnance Survey enlarged mapping that is hosted on the Geograph website, with these details being posted on the RHB Yahoo Group forum on 01.05.12.

Prior to this notification Mark Jackson had listed this hill as a Subhump with c 92m of drop based on the 164m summit spot height given to a triangulation pillar on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 72m based on bwlch contouring at 10m intervals, interpolation of bwlch contouring was helped by the use of 5m contour intervals on the Ordnance Survey enlarged mapping hosted on the Geograph website and the use of a 77m spot height centralised on the area of the bwlch, and when coupled with this hill’s 164m summit spot height these values give this hill 87m of drop, which is insufficient for it to retain its Subhump status.

Extract from the Ordnance Survey enlarged mapping hosted on the Geograph website showing the 5m contour intervals at the bwlch and the 77m spot height

The hill appears under the name of Pen Gilfach-y-rhew in the listing of the Humps, this is an invented name based on the name of the farm to the north-west of the hill’s summit.  As this hill comprises bounded land its details were examined on the Tithe map to the parish of Abergwili, and the enclosed land at the summit of this hill where the triangulation pillar is situated is named Cae Llan.

Extract from the Ordnance Survey Six-Inch map showing that Gilfach-y-rhew is the name of a farm and not the name of the hill

The hill is adjoined to the Mynydd Pencarreg range of hills and is situated overlooking the A40 road and the Afon Annell and Afon Tywi (River Towy) to the south-east, with the town of Caerfyrddin (Carmarthen) towards the west south-west.

The deletion of this hill from Subhump status was accepted by Mark Jackson on the 06.05.12 and the listing of the Humps was updated accordingly.

The full details for the hill are:

Name:  Pen Gilfach-y-rhew (as listed in the Humps)

Summit Height:  164m

OS 1:50,000 map:  159

OS 1:25,000 map:  177

Summit Grid Reference:  SN 45827 22317

Drop:  87m

Myrddyn Phillips (September 2017)